Matplotlib for Python Developers

307 Pages·2009·11.378 MB·English

by  Tosi, Sandro

Matplotlib for Python
Developers

Build remarkable publication quality plots the easy way
Sandro Tosi
BIRMINGHAM - MUMBAI
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
Matplotlib for Python Developers
Copyright © 2009 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval
system, or transmitted in any form or by any means, without the prior written
permission of the publisher, except in the case of brief quotations embedded in
critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of
the information presented. However, the information contained in this book is sold
without warranty, either express or implied. Neither the author, Packt Publishing,
nor its dealers or distributors will be held liable for any damages caused or alleged to
be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all the
companies and products mentioned in this book by the appropriate use of capitals.
However, Packt Publishing cannot guarantee the accuracy of this information.
First published: November 2009
Production Reference: 2221009
Published by Packt Publishing Ltd.
32 Lincoln Road
Olton
Birmingham, B27 6PA, UK.
ISBN 978-1-847197-90-0
www.packtpub.com
Cover Image by Raghuram Ashok ([email protected])
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
Credits
Author Editorial Team Leader
Sandro Tosi Akshara Aware
Reviewers
Project Team Leader
Michael Droettboom
Priya Mukherji
Reinier Heeres
Project Coordinator
Acquisition Editor
Zainab Bagasrawala
Usha Iyer
Proofreader
Development Editor
Lesley Harrison
Rakesh Shejwal
Graphics
Technical Editor
Nilesh Mohite
Namita Sahni
Production Coordinator
Copy Editor Adline Swetha Jesuthas
Leonard D'Silva
Cover Work
Adline Swetha Jesuthas
Indexers
Monica Ajmera
Hemangini Bari
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
About the Author
Sandro Tosi was born in Firenze (Italy) in the early 80s, and graduated with a B.Sc.
in Computer Science from the University of Firenze.
His personal passions for Linux, Python (and programming), and computer
technology are luckily a part of his daily job, where he has gained a lot of experience
in systems and applications management, database administration, as well as project
management and development.
After having worked for five years as an EAI and an Application architect in an
energy multinational, he's now working as a system administrator for an important
European Internet company.
I'd like to thank Laura, who has assisted and supported me while
writing this book.
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
About the Reviewers
Michael Droettboom holds a Master's Degree in Computer Music Research
from The Johns Hopkins University. His research in optical music recognition lead
to the development of the Gamera document image analysis framework, which has
been used to recognize features in documents as diverse as medieval manuscript,
Navajo texts, historical Scottish census data, and early American sheet music. His
focus on computer graphics has lead to specializations in consumer electronics,
computer-assisted engineering, and most recently, the science software for the Space
Telescope Science Institute. He is currently one of the most active developers on the
Matplotlib project.
I wish to thank my son, Kai, for asking all the hard questions.
Reinier Heeres has an MSc degree in Applied Physics from the Delft University of
Technology, The Netherlands. He is currently pursuing a PhD there in the Quantum
Transport group of the nanoscience department.
He has previously worked on Sugar, the child-friendly user interface mainly in use
by One Laptop Per Child's $100 laptop. For this project, he designed the Calculator
application.
Recently, he revived and extended the 3D plotting functionalities for Matplotlib to
make it an excellent 2D graphing library, and a simple 3D plotting tool again.
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
Table of Contents
Preface 1
Chapter 1: Introduction to Matplotlib 7
Merits of Matplotlib 8
Matplotlib web sites and online documentation 10
Output formats and backends 10
Output formats 11
Backends 12
About dependencies 13
Build dependencies 15
Installing Matplotlib 15
Installing Matplotlib on Linux 15
Installing Matplotlib on Windows 16
Installing Matplotlib on Mac OS X 16
Installing Matplotlib using packaged Python distributions 17
Installing Matplotlib from source code 17
Testing our installation 18
Summary 19
Chapter 2: Getting Started with Matplotlib 21
First plots with Matplotlib 21
Multiline plots 25
A brief introduction to NumPy arrays 27
Grid, axes, and labels 28
Adding a grid 28
Handling axes 29
Adding labels 31
Titles and legends 32
Adding a title 32
Adding a legend 33
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
Table of Contents
A complete example 35
Saving plots to a file 36
Interactive navigation toolbar 38
IPython support 40
Controlling the interactive mode 42
Suppressing functions output 43
Configuring Matplotlib 43
Configuration files 44
Configuring through the Python code 45
Selecting backend from code 46
Summary 47
Chapter 3: Decorate Graphs with Plot Styles and Types 49
Markers and line styles 49
Control colors 50
Specifying styles in multiline plots 52
Control line styles 52
Control marker styles 53
Finer control with keyword arguments 56
Handling X and Y ticks 58
Plot types 59
Histogram charts 59
Error bar charts 61
Bar charts 63
Pie charts 67
Scatter plots 69
Polar charts 71
Navigation Toolbar with polar plots 73
Control radial and angular grids 73
Text inside figure, annotations, and arrows 74
Text inside figure 74
Annotations 75
Arrows 77
Summary 79
Chapter 4: Advanced Matplotlib 81
Object-oriented versus MATLAB styles 81
A brief introduction to Matplotlib objects 85
Our first (simple) example of OO Matplotlib 85
Subplots 86
Multiple figures 88
Additional Y (or X) axes 89
[ ii ]
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
Table of Contents
Logarithmic axes 91
Share axes 92
Plotting dates 94
Date formatting 95
Axes formatting with axes tick locators and formatters 96
Custom formatters and locators 99
Text properties, fonts, and LaTeX 99
Fonts 101
Using LaTeX formatting 102
Mathtext 103
External TeX renderer 104
Contour plots and image plotting 106
Contour plots 106
Image plotting 109
Summary 111
Chapter 5: Embedding Matplotlib in GTK+ 113
A brief introduction to GTK+ 113
Introduction to GTK+ signal system 115
Embedding a Matplotlib figure in a GTK+ window 116
Including a navigation toolbar 119
Real-time plots update 123
Embedding Matplotlib in a Glade application 132
Designing the GUI using Glade 132
Code to use Glade GUI 135
Summary 144
Chapter 6: Embedding Matplotlib in Qt 4 145
Brief introduction to Qt 4 and PyQt4 145
Embedding a Matplotlib figure in a Qt window 147
Including a navigation toolbar 151
Real-time update of a Matplotlib graph 156
Embedding Matplotlib in a GUI made with Qt Designer 165
Designing the GUI using Qt Designer 165
Code to use the Qt Designer GUI 168
Introduction to signals and slots 171
Returning to the example 172
Summary 179
Chapter 7: Embedding Matplotlib in wxWidgets 181
Brief introduction to wxWidgets and wxPython 181
Embedding a Matplotlib figure in a wxFrame 182
Including a navigation toolbar 186
[ iii ]
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104
Table of Contents
Real-time plots update 192
Embedding Matplotlib in a GUI made with wxGlade 203
Summary 213
Chapter 8: Matplotlib for the Web 215
Matplotlib and CGI 216
What is CGI 216
Configuring Apache for CGI execution 216
Simple CGI example 218
Matplotlib in a CGI script 219
Passing parameters to a CGI script 220
Matplotlib and mod_python 223
What is mod_python 223
Apache configuration for mod_python 224
Matplotlib in a mod_python example 226
Matplotlib and mod_python's Python Server Pages 228
Web Frameworks and MVC 231
Matplotlib and Django 232
What is Django 232
Matplotlib in a Django application 233
Matplotlib and Pylons 237
What is Pylons 237
Matplotlib in a Pylons application 238
Summary 242
Chapter 9: Matplotlib in the Real World 243
Plotting data from a database 244
Plotting data from the Web 247
Plotting data by parsing an Apache log file 250
Plotting data from a CSV file 256
Plotting extrapolated data using curve fitting 261
Tools using Matplotlib 267
NetworkX 267
Mpmath 269
Plotting geographical data 271
First example 272
Using satellite background 274
Plot data over a map 275
Plotting shapefiles with Basemap 277
Summary 279
Index 281
[ iv ]
This material is copyright and is licensed for the sole use by Jillian Fraser on 20th November 2009
111 Sutter Street, Suite 1800, San Francisco, , 94104